More and more frequently, modern industrial facilities are utilizing unmanned vehicles to transport and handle material as opposed to overhead cranes, fork lift trucks and the like. The use of such vehicles substantially reduces the required factory manpower thereby substantially reducing factory costs. Typically, these vehicles, often called automated guided vehicles, are powered by on-board lead-acid or nickel-cadmium storage type batteries and follow a path around the facility usually defined by a wire embedded in the floor in a predetermined fixed pattern or optical tape affixed to the floor in a predetermined fixed pattern. These vehicles usually communicate with a central control through atmospheric radio frequency transmissions.
These types of vehicles are, however, not without their problems. Of prime concern is the inability of the user to readily alter the path of the vehicle because the wire imbedded in the floor is a rather permanent fixture. If a change in path is desired, it is necessary to shut down the facility and physically relocate the wire in the floor.
Another aggravation to the user of the typical vehicles is that some factory environments interfere with the radio signals to the vehicle. This can occur even where only short transmission distances are involved and can be solved, if at all, only with sophisticated and expensive transmission systems.
Finally, the use of battery power has its deficiencies. Not only do batteries provide a limited quantity of power, but they also need frequent recharging resulting in equipment downtime. Such recharging is not only time-consuming but it could often be hazardous with many expensive precautions having to be taken to avoid injury due to, for example, exposure to a caustic chemical. Furthermore, the mere existence of the batteries themselves on the vehicle consumes valuable vehicle space and utilizes some of the weight capacity of the vehicle.
In short, the prior art automated guided vehicles, of which we are aware, do not provide the total answer for an efficient, versatile unmanned material handling vehicle.